Material handling apparatus



Nov. 7, 1944. w. RUDDOCK MATERIAL HANDLING APPARATUS I Filed Nov. 10, 1941 Z'Sheets-Shet 1' W/[. L MM K000 0oz,

' INVENTOR ATTORNEYS Nov. 7, 1944. w. RUDDOCK MATERIAL HANDLING APPARATUS Filed Nov. 10, 1941 INVENTOR ATTORNEYS 2 Sheets-Sheet 2 W/LL IAM Euooocxc,

Patented Nov. 7, 1944 MATERIAL HANDLING APPARATUS William Ruddock, South Pasadena, calm, assignor of one-half to Marion P. McCafirey, Los

Angeles, Calif.

Application November 10, 1941, Serial No. 418,557 18 Claims. (Cl. 214-140) This invention relates to material handlin apparatus and more particularly to that type of structure which includes a movable bucket or dipper.

A large class of materialhandling devices inb machines with a bucket of such a width as to necessitate the provision of some means for moving the arm which acts upon two points widely spaced transverse of the arm. As cables form a convenient means for transferring power from the prime mover of the machines to the arm or dipper, a pair of cables spaced transversel and attached to transversely spaced points on the dip per or on the arm is a customary method of mov ing the dipper and arm. The cables are controlled by one or two winches which are in turn controlled by the prime mover of the machine.

The use of a pair of hoisting lines theoretically should permit the distribution of the total load to be lifted between these lines. However, this theoretical condition is rarely if ever attained. It. is extremely diflicult when assemblin the machine to assure that both of the cables are of the proper length so that they each take an equal share of the load. In addition to this difliculty, it is practically impossible to assure-that a pair of hoisting drums, or even a single drum, spooling two lines, will wind them up at the same speed. That is, it is impossible to assure that a given number of rotations of the hoisting drums will wind the same length of cable on the drums. This results in one of the other of the cables taking a disproportionate share of the load. It also-introduces twisting. strains on the entire mechanism.

In addition to the above difdculties which are more or less inherent in any structure which employs a pair of cables for lifting a single object unless special precautions are taken, cable lifting devices as a classyare subjected to great stresses and strains because of the development of impact loads when the drum is suddenlystopped by means of the brakes. Development of slackin the hoisting cables and sudden dropping of the load also cause impact loads upon the entire mechanism, and particularly upon the hoisting cables. For this reason the life of the cables is comparatively brief and considerable time is lost by the snapping of one or both of the cables during use of the machine.

It is an object of the present inventionto providea mechanism for applying forces to spaced points on a bucket and arm assembly which forces are always equal to each other. I

It is a,further object of the present invention to provide adevice which will assure equal tension in the hoisting cables of a machine of the class described.

It is a further object of the present invention to provide adevice which will compensate for uneven spooling of a pair of cables liftin a single object in a machine of the class described.

It is a further object of the present invention to prevent the development of twisting stresses in a machine of this class.

It is a further object of the present invention to provide means which will prevent the development of 'slack in hoisting'cables in a machine of this nature. v

It is a further object of the present invention to prevent the development of impact loads upon the parts of the machine and upon the cables resulting from a sudden stoppage of the load when being moved in a downward direction.

It is a further object of the present invention to provide means for permitting the load to be resiliently supported by the cables.

This invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of several embodiments of the invention. For this purpose there are shown two forms in the drawings accompanying and forming part of the present specification. These forms, which illustrate the general principles of the invention, will now be described in detail; but it is to be understood that this detailed description is -not to be taken in a" limiting sense, since the scope of the invention is bestdeflned by the appended claims.

Referring now to the drawings:

lj'igure 1 is a side elevation of one type of material handling device employing the present invention;

Figure 2 is an enlarged view'taken on line 2-2 of Figure 1;

Figure 3 is an enlarged longitudinal sectional view taken through part of the mechanism embodying this invention;

Figures 4, 5 and 6 are sections taken along lines 4-4, 5-5 and 6-6 respectively of Figure 3; and,

. Number 2,260,539.

' drum ll.

cables l and i5 are widely separated, it is con- 2 n l a Figure '1 is a view similar to Figure 3 but of a modified form of the present invention.

Referring first to Figure 1, there is shown a tractor shovel of the type described in my Patent frame it mounted on caterpillar treads Ii for movement over the ground. Supported on this frame Ill is a hoisting arm or boom l2 which carries at one end a dipper 13 for carrying a load of material. This hoisting arm i2 is pivoted to the tractor frame as at an elevated point It.

This'machine comprises a It can be seen that a load can be lifted and conveyed by raising the dipper carryin end of the arm l2. In order to accomplish this'raising of. the dipper a pair of cables is provided. In the instant type of machine these cables are operatively connected to the bucket for the purpose of controlling the bucket, but it is to be understood that so far as the present invention is concemed these cables could be operatively connected to the hoisting arm itself and the bucket controlled by some other mechanism. The present invention will be described with this inmind.

The two hoisting cableswhlch are operatively connected to the dipper l3 are designated l5 and I6. Each' of these'cables is led to a hoisting It is. to be'understood that a the venient to supplya drumfor each ofthese cables, only one or which is shown in the drawings. These drums are driven from a common shaft which is connected to a prime mover and provided to raise, lower, -or hold the dipper. As was mentioned above, the use of a pair of cables and a pair of hoisting drums introduces complications because of the diiilculty of assurthe same time'the motion of one cable without a corresponding motion'in the other will cause a motion of the movable sheaves toward or away .22 extending from the dipper by means of pins 23 passing through said forks and the lugs. This casing serves as the support for the sheaves above mentioned.

The stationary sheavesZl' are supported on.

the casing 20 for rotation only. As shown in Figures. 3 and 6, each sheave 2| is mounted near an end of the casing 20, in the interior thereof,

but projecting through slots in the casing.

Any suitable mounting means may be used, but

1 other considerations dictate that when the sheaves with a suitable brake for control as it is desired ln'g}that the tension in each of the cables is equal to that in the other on installation, and also because of the likelihood of uneven spooling of the cables on the hoisting drums,- which tends to twist I the frame of the dipper carrying arm and to cause the development of excessive tension on one of the cables. Briefly, what applicant proposes to do is to make the cables I! and it one continuous cable element, which is not secured to the bucket l3 directly, but passes around a pulley system so that the tension in one reach of the cable must .of necessity be' equal to that in the other. In addition to this, applicant proposes to provide a suitable spring means'to give the cheat of resiliency to the cable, or a change in the effective lengtho'f the cable, These two expedients' are conveniently attained in the same mechanism, which will now be described.

As shown in Figures 2 to 5 a bridge structure is pivotally attached to the bucket, extendin transversely thereof and supporting a pair of spaced sheaves respectively adjacent its opposite 1 ends. These sheaves serve to transmit the lifting effort of the cables l5 and ii to the dipper 'but permit the equalization of the tensions in the cables l5 and U. The tension in cable I5 is of necessity equal to that in cable 16 as they are mere portions ofthe same cable.- A second pair finally aroundthe other stationary sheave to the' other hoisting drum. It can be seen that this will permit the endless cable to run freely frcm' one side of the machine to the other to equalize the tension of the portions l5 and 15,. whil at:

2| are removed the interior of the casing 20 be .comparatively'open. For this reason sleeves 26 are provided'on opposite sides of the sheaves 24,

and bosses 21 are secured to the casing 20 at diametrically opposite points. A suitable shaft 28 passes through the bosses 21, the sleeves 26, and the hubs of the sheaves 2!. It can be seen that the sleeves 26 can be inserted in the casing 20, followed by insertion of the sheaves, after which the shafts 28 can be passed through them. Any suitable means for holding the shafts-in position may be utilized, as for instance the cotter pins 29. The shafts may be mounted to turn with the sheaves 24, or the sheaves may run freely thereon, whichever is deemed most convenient.

The travelling sheaves are mounted, upon carriers which slide along the casing 20. As shown in Figures 3, 4 and 5, each of the sheaves 3D is mounted upon a body 3|, which is slotted to ac oommodate it. A shaft 32 serves to rotatably therealong' as the carriers move.

mount the sheave, and may be simply in the form of a nut and bolt if 'no more elaborate construction is desired. As shown in Figure 3, each -01 the slots 25 extends from, the stationary sheave to a point near the middle'of the casing 20. The carriers 3| and the sheaves 30 extend through the slots 25, and said carriers are. uided therein for movement longitudinally of the casing. As a further aid in supporting the carriers 3|, and guiding them in their longitudinal movement along the casing 20, they are each provided with ears 3!, which conform with the exterior conflgurationof the casing and slide As it is necessary that some means be provided to permit the initial insertion of the carriers 3| into the interior of the casing 20-, the ears on one side of the carrier may be made removable, this being accomplished simply by providing lugs 35 on the body of the carrier, to which the ears 34 are secured by means of bolts or other suitable fasteners 36. The carriers are intended to be held apart by some yleldable means, which is shown as bein in the form of aspring 33 interposed between them within the casing 20. 'The ends of the spring extend over bosses 31 secured to and eX- tending inwardlyfrom the carriers 3|. These bosses serve to properly position the spring in the casing 20 and prevent it from jamming between the carriers and the casing. Because of the pres- ,ence of the bosses 31, it is convenient to provide an enlargement in the slots 25 to'permit the insertion of the carriages through these slots. These enlargements have been shown at 25a in the regions occupied by the stationary sheaves 24, it being understood of course, that the stationary sheaves are to be inserted after the traveling sheaves are in proper position.

In order to prevent the travelling sheaves 30 from coming into'contact with the stationary sheaves 24 in their outermost positions of travel, any suitable stop means may be provided. In the present instance, this has been done by the aid of the bolts 38, which are simply passed through the walls 01' the casing and form abutments against which the traveling carriers 3| engage.

There is provided exteriorly of the casing 20 a second coil spring 39. It will be noted that this coil spring is shorter than thespring 33 within the casing, and that it does not normally engage the traveling ,carriers. However, if the cables l5 and it are subjected to an impact load, as by suddenly stopping the drums H, the ininternal spring 33 willfcompress sufflciently to permit the spring 39 to become engaged by the carriers 3|. Thus the spring 39 acts as an auxiliary spring and assists the interior spring 33 to cushion the mechanism against the deleterious eil'ects of such impact loads. It will be noted that this spring 39 is free to slide along the cas-' ing 20, as it cannot be assumed"'thatthe travel of each of the carriers will be equal to'that of' the other, and thus the spring 39 isso mounted,

bles I5 or it, the continuous cable of'which these cables iorm segments will run freely from one end of the device to the other, passing around all the sheaves, until the tension on the cables [5 and i6 is equalized. Qn the other hand, if

when both cables are under equal tension,- an excessive load is placed on the cables by any cause whatever, such. as sudden stopping of the windingdrums II, the travelling carriers will be forced together compressing spring 33, and; if the load is suflicien't, also compressing the spring 39. It is 01' course to be understood that both of these functions can take place simultaneously,

It is to be understood, of course, that the various sheaves must be slightly staggered so that the various lays of the cable will not interfere with each other. This construction is well-known to those engaged in this art and it is therefore ,considered unnecessary to show this particular construction. It isalso to be understood that cushioning efiect. The cushioning eiTect can be taken care of in other parts of the machine 'or omitted entirely if so, desired.

In this form of device, a casing 50 is secured to the dipper or other part of the machine by means of the pivots 5|, as in the first described device. A pair of sheaves 52 is rotatably mounted in the casing 59, on axles 53, in any suitable manner. Slots 54 are provided in the casing for the passage of the sheaves and cables through the walls thereof.

The cable designated 55, is secured at each end to the winding drums, and simply passes-over both of the sheaves, in the manner shown, and is thus always maintained under equal tension on both sides of the machine. I

Iclaimr 1. In a material handling device, the combination of a material engaging element and arm assembly mounted for movement to raise said element, a mechanism for applying forces to. said assembly at spaced points thereon to raise said element, means for equalizing said forces, said mechanism including yielding means positioned between said points permitting resilient movement of sad assembly.

. 2. In a material handling device, the combination of a material engaging element and arm assemblymounted for movement to raise said element, apair of force producing elements, a

pair of sheaves connected to; said assembly at spaced points thereon, a cable element extending from one of said force producing elements, passing over said sheaves and returning to the other force producing element, means forming a loop in said cable element between said sheaves,

and spring means operatively connected to said loop to yield and permit resilient motion of said assembly.

3. In a material handling device, the combination 01' a material engaging element. and arm assembly mounted for movement to raise said element, a pair of force producing elements, a cable attached at its ends to said force producing elements, a pair. of sheaves mounted at spaced points on said assembly, and a third sheave resiliently mounted with respect to thejfirst mentionedsheaves, said cable passing from one force producing element, around one offthe first mentioned sheaves, around'the resiliently mounted sheave, around the other sheave, and to the other force producing element, whereby the portions of the cable betweenthe force producing elements and the first mentioned sheaves .are maintained under equal tension and the assembly is resiliently supported by said cable.

" arm assembly mounted for movement to raise the exterior spring 39 could be arranged withinthe spring 33 provided suitable guides are utilized to hold it out of engagement with the spring-.33.-

understood that the tubular'com' It is also to be struction of the casing 20 is merely for the purpose of illustration, as this member might as well be formed .of two facing channels welded together in such a manner as to'leave theneces- 'sary guide slots between them. Various other modifications will readily suggest themselves.

In addition to the above device, a device is shown in Figure? of a similar nature. It will be noted, however, that this form of device equalizes the tension in the cables, and does not have any said element, a pair of force producing elements, a cable having its ends attached to said elements, a pair of sheaves mounted in, fixed spaced relation on said assembly, a second pair of sheaves mounted for resilient movement towards each other, said cable passing from one force producing element, around one of the fixed sheaves, around both the resiliently mounted sheaves, and

around the other ofsaid fixed sheaves to the other force producing element, whereby the portions of the cable between the force producing elements and the fixed sheaves are maintained under equal tension and the assembly is yieldably supported by said cable.

5. A device for transmitting the tension in a pair of portions to a movable element comprisassembly mounted for movement to raise or lower said element, a pair of sheaves mounted at spaced points on said assembly, a cable element passing between said sheaves, and having a reach extending from each sheave, force producing mechanism, each reach being attached to said mechanism, and means resiliently and continuously urging a reduction in the effective length of said cable element.

7. In material handling apparatus, an assembly supported so as to be raised or lowered, a cable element having two reaches extending from the assembly, means for applying substantially equal forces simultaneously to each reach, means for transferring force between the assembly and the cable element comprising equalizing means for maintaining the forces acting in the reaches substantially equal at all times, and means for absorbing shock in the cable element, comprising a pair of sheaves slidably mounted on the assembly and about which the cable is looped,

and means resiliently opposing movement of the sheaves in response to forces acting on the cable element.

8. In material handling apparatus, an assembly supported so as to be raised or lowered, a cable element having two reaches extending from the assembly, means for applying substantially equal forces simultaneously to each reach, means for transferring force between the assembly and the cable element comprising equalizing means for maintaining the forces acting in the reaches substantially equal at all times, and means for absorbing shock in the cable element, comprising a pair of sheaves slidably mounted on the assembly and about which the cable is looped, spring means between said sheaves opposing movement of the sheaves toward each other in response to forces acting on the cable element, and additional spring means between the sheaves for assistingthe first mentioned spring means and becoming effective only after a predetermined movement of the sheaves. a

9. In material handling apparatus, a material engaging element and arm assembly mounted for movement to raise and lower said element, a pair of transversely spaced sheaves mounted on said assembly, force exerting mechanism for controlling said movement and including a cable element operatively connected to the assembly by means of said sheaves, and having a portion extending between the sheaves, and spring means acting continuously on the cable between said sheaves to tension the cable.

10. In material handling apparatus, a material engaging element and arm assembly mounted for movement to raise and lower said element, a pair of transversely spaced sheaves mounted on said assembly, force exerting mechanism for controlling said movement and including a cable element operatively connected to the assembly by means of said sheaves, and having a portion extending between the sheaves, and mechanism carried by said assembly forming a resilient operating connection between the assembly and that portion of the cable between the sheaves.

11. In material handling apparatus, a material engaging element and arm assembly mounted for movement to raise and lower said element, a pair of transversely spaced sheaves mounted onsaid assembly, force exerting mechanism for controlling said movement and including a cable element operatively connected to the assembly by means of said sheaves, and having a portion extending between the sheaves, and mechanism carried by said assembly including a compression spring interposed between the cable and the assembly, the force of the spring opposing the force in the cable, and means whereby a portion only of the 'force acting in the cable acts on said spring.

12. In material handling apparatus, a material engaging element, an arm on which said element is mounted for movement with respect to said arm, said arm being mounted for movement to raise and lower said element, means for controllin'g the movement of said element with respect to the arm comprising, a cable element having a pair of reaches, a bridge structure movably mounted on said material engaging element and extending transversely thereof, means operatively securing the reaches of saidcable element to the bridge structure adjacent the opposite ends thereof, said means acting to equalize the tension in said reaches, and shock absorbing means carried by said structure permitting resilient movement of the material engaging element with respect to the cable element regardless of the position of said structure with respect to said material engaging element.

13. In material handling apparatus, a material mounting said element on said arm for movement 'with respect to said arm, said arm being mounted for movement to raise and lower said element, a bridge structure extending transversely of said element, means pivotally mounting said structure on said element, the pivotal mounting means for said structure and said element having parallel axes, means for controlling the movement of said element with respect to the arm comprising a cable element, and means operatively securing the cable element to the bridge structure, said means permitting resilient movement of the material engaging element with respect to the cable element.

14. In material handling apparatus, a material engaging element, an arm on which said element is mounted for movement with respect to said arm, said arm being mounted for movement to raise and lower said element, means for controlling the movement of said element with respect to the arm comprising, a cable element, sheaves operatively secured to said material engaging element adjacent the opposite ends thereof, said cable element passing over said sheaves so aswhereby the laterally extending portions of the cable element are maintained in the same planes with respect to the sheaves.

15. In material handling apparatus, a material engaging element and arm assembly, mounted for movement to raise and lower said element, force engaging element and arm assembly, mounted for movement to raise and lower said element, force exerting mechanism for controlling said move ment and including a cable element operatively connected to the material engaging element, spring means arranged to be compressed by the cable element upon'normal' operation of said material engaging element by the cable, and means whereby said spring acts to resiliently tension the cable for absorbingimpact loads thereon.

17. In material handling apparatus, a material engagingelement and arm assembly, mounted for movement to raise and lower'said element, force exerting mechanism for controlling 'said movement and including a cable element operatively connected to the assembly at transversely spaced points thereon, spring means arranged to be compressed by the cable element. upon normal operation of said assembly by the cable, and. means whereby said spring acts to resiliently tension the cable for absorbing impact loads thereon.

18. In material handling apparatus, a material engaging element and arm assembly mounted for movement to raise and lower said element, force exerting mechanism for controlling said movement and including a cable element operatively' connectedto the assembly at transversely spaced points thereon,-means for equalizing the force exerted by the cable element at said points, and

spring meansacting continuously to maintain tension in the cable.

' RUDDOCK. 

